The invention concerns a mobile radiotelephone system having a service station which is in radio contact with, and exchanges digital data with, at least one mobile broadcast station via intermediately connected switching units. The mobile broadcast station contains a microprocessor for controlling the data communication. The microprocessor accesses a first memory segment in which a control program to be processed by the microprocessor is stored. The invention further concerns a mobile broadcast station, as well as a method for the operation of the mobile radiotelephone system.
A known mobile radiotelephone system is the digital cellular mobile radiotelephone system D900 by Siemens, described in a brochure, "Siemens D900 mobile radiotelephone system," 1994, published by the Business Division for Mobile Radiotelephone Networks, Hoffmannstra.beta.e 51, D-81539 Munich, Siemens Aktiengesellschaft. A mobile radiotelephone system of this type has a central service station which exchanges digital data with a mobile telephone via intermediately connected switching units, for example base stations for the coverage of cell-type spaces in the radiotelephone network. Further digitally operated terminal devices may be connected to the mobile telephone, such as telefax devices. The control of the data communication at the mobile telephone is handled by a microprocessor, e.g. the control of the receiving unit, the signaling unit and the transmission unit, as well as of peripheral components such as the keyboard and the display unit of the mobile telephone. The microprocessor receives its control commands from a control program stored in a read-only memory. The read-only memory, e.g. a ROM or an EPROM, is plugged or soldered onto a circuit board of the mobile telephone as a component. Another possibility is that the read-only memory can be programmed from the outside by means of an external programming unit to which the mobile telephone is connected via an interface module.
In the course of the continuing development of mobile radiotelephone technology, there arise new control programs that are more efficient, or in which flaws that appeared in previous control programs have been eliminated. In order to be able to use new control programs, the mobile telephones normally have to be taken to a service station, and the read-only memories have to be loaded with the data of the new control program, or the read-only modules have to be exchanged. A procedure of this type is complicated and leads to a high technological and economic expense.